Saturday, October 30, 2004

Chapter 7: DNA Technology (Definitions)

Genes- nucleotide sequences coding for a product.
Codon- sets of 3 nucleotides that will code for one amino acid.
Genome- a cell's entire genetic compliment, including its genes.
Chromosomes- segments of DNA.
Plasmids- small circular molecules of DNA that replicate independently of the chromosome.
Histones- globular proteins
Genotype- actual set of genes in its genome.
Phenotype- physical features and functional traits of an organism, including characteristics.
Transcription- gene information is copied as RNA nucleotide sequences.
Translation- Polypeptides are synthesized by RNA molecules in ribosomes.
Central Dogma- the processes of transcription and translation.
Transduction- a method of horizontal gene transfer.
Promoter- a nucleotide sequence located near the beginning of a gene and initiates transcription.
Mutation- a change in the nucleotide base sequence of a genome, particularly its genes.
Point Mutations- when just one or a few nucleotide base pairs are affected.
Frameshift Mutations- insertions and deletions creating new sequences of codons that result in largely altered polypeptide sequences, usually affecting proteins more than substitutions.
Thymine Dimers- mutation caused by nonionizing radiation in the form of UV light, causing adjacent thymine bases to covalently bond to one another.
Light Repair- prokaryotic DNA photolysase enzyme breaks bond between adjoining thymine nucleotides, restoring the original DNA sequence.
Dark Repair- enzymes cut damaged DNA sections from a molecule, creating a gap that is repaired by DNA polymerase and ligase.
Excision Repair- enzymes exise DNA strand that is in error, and filling the gap with DNA polymerase.
SOS Response- prokaryotic cells with extensive DNA damage use various processes to induce DNA polymerase to copy the damaged DNA.
Bacteriophage- a virus that infects a bacteria
Conjugation- horizontal gene transfer where bacteria containing a fertility plasmid forms a conjugation pilus that attaches and transfers plasmid genes to a recipient.